A validation issue was addressed with improved input sanitization. This issue is fixed in iOS 15.3 and iPadOS 15.3, watchOS 8.4, tvOS 15.3, Safari 15.3, macOS Monterey 12.2. Processing a maliciously crafted mail message may lead to running arbitrary javascript.
https://support.apple.com/en-us/HT213256
https://support.apple.com/en-us/102770
https://support.apple.com/en-us/103177
https://support.apple.com/en-us/103176
https://support.apple.com/en-us/103175
https://support.apple.com/en-us/103172
https://support.apple.com/en-us/102848
https://support.apple.com/kb/HT213256
https://support.apple.com/kb/HT213255
https://support.apple.com/kb/HT213185
https://support.apple.com/en-us/HT213059
https://support.apple.com/en-us/HT213058
https://support.apple.com/en-us/HT213057
https://support.apple.com/en-us/HT213054
https://support.apple.com/en-us/HT213053
https://security.gentoo.org/glsa/202208-39